Speedometer



I 111518,1941.. E .F BACON 2,248,325

SPEEDOMETER I original Filed Aug. 26, 1937 nventor Bg S4 Gttornegs Patented July 8, 1941 SPEEDOMETER Elbridge F. Bacon, Flint, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Original application August 26, 1937, Serial No. 161,089. Divided and this application March 7, 1940, Serial No. 322,642

3 Claims.

This invention relates to the illumination of indicating instruments and has been designed more particularly as an improved provision for the illumination of a speedometer and odometer combination for use on vehicles.

An object of the invention is to improve the illumination of the speed and distance markings of such a device for use at night.

Another object is to'provide such illumination as will conceal the light from a source except such light as is directed to the parts which need to be illuminated.

Another object is to accomplish the above objects by a construction wherein one of the two parts of the combined instrument is visible through a transparent member associated with the other part of the instrument.

Other objects and advantages will be understood from the following description.

On the drawing:

Figure l is a vertical half section through one embodiment of the invention.

Figure 2 is a view in elevation of the instrument shown in Figure 1.

Figure 3 is a perspective of one of the parts used in the instrument.

Figure 4 is a perspective of a part which may be used in place of the part shown in Figure 3.

The instrument shown in Figure 1 -comprises a cup-shaped member II carrying operating mechanism, not shown. A housing I5 is secured in any convenient way to the member I I and has a radially directed ange. A bezel I1 is used to secure in position relative to housing I5 and other parts of the instrument a metal plate 2| and a glass cover 23. Extending into the housing I5 is a light bulb 21 mounted in a socket 25. Light from the bulb illuminates the interior oi the housing. Suitable openings 29 in the plate 2| permit the passage of light from within the housing and into the glass 23. Etched or otherwise formed on the glass are markings 26 which take the form of numerals to represent the speed at which the vehicle is traveling. The light which is transmitted through openings 29 to the glass is interiorly reflected through the glass, refracted and then reflected from the markings 26. At night the glass as a whole is not visible, only the etched portions are seen by the operator.

The degree of light entering the glass and its color can be controlled by painting the front surface of the glass opposite openings 29 either white or some other desired color. The white or painted surface aids in dispersing the light through the glass thereby improving the lighted appearance of the numerals.

At 3| is represented a more or less conventional odometer mechanism. The odometer comprises a plurality of gure Wheels as shown. The gures are seen by the observer through' glass 23, through the large opening in plate 2| and through openings 35 in another plate 31, this last mentioned plate being suitably secured by fastening means, not shown, on the frame of the odometer. Plate 31 covers the operating parts of the instrument and together with plate 2| prevents direct light from bulb 21 from reaching the observer. To accomplish this result it will be seen that the outer margin of plate 31" is considerably beyond the opening in plate 2|.

The speedometer mechanism is provided with a rotating spindle 36 extending through a small aperture in plate 31". Stem 39 has secured at its end a transparent disc 1| which is circular in outline. About the periphery of the disc is a metal ring 13, U-shape in section. This ring is clamped over the edge of the disc 1I as shown in Figure 3. At one point in the periphery the ring has a painted tip 15 extending radially from the ring. Light from the bulb 21 passes between the plates 2| and 31" and is reflected from the tip 15,. The position of this tip relative to the figures etched on the glass at 26 indicates the speed at which the car is traveling. The odometer gures are seen through the glass 23, through the large opening in plate 2| and through the transparent disc 1I.

In Figure 4 there is a slight modication of the pointer element. It is designated by numeral 1I It, too, is a transparent circular disc. Formed on its peripheral margin. is a thickened rim portion 13', this rim being of the same material as the disc and, at one point, provided with a radially extending and painted tip 15'. It will be obvious that the light is transmitted from the source to illuminate the several parts in this modified form in preciselythe same way as described in connection with the form using disc 1 I.

This application is a. division of my prior application for speedometer, Serial No. 161,089, filed August 26, 1937.

I claim:

1. An indicating instrument comprising a housing, a light source therein, spaced inner and outer opaque members having overlapping regions to prevent direct transmission of light from said source, the outer of said members havmg an enlarged opening, the inner of said members having a small aperture, a rotatable instrument spindle extending through said aperture, a transparent disc carried by said spindle and located between said plates, said transparent disc having a marginal reecting pointer, means forming markings to cooperate with said pointer to give readings, the inner of said opaque plates having an opening through which and through said transparent pointer disc the movable members of a second indicating device may be seen.

2. A pointer for an indicating instrument, said pointer being in the form of a transparent dise, said disc having a marginal bead of circular outline and a light reflecting tip extending radially outward from said bead.

3. The invention dened by claim 2, said bead and tip being integral with the disc.

ELBRIDGE' F. BACON. 

